IN-VITRO REGENERATION OF PLANTLETS OF SCOTS PINE (PINUS-SYLVESTRIS) WITH MYCORRHIZAL ROOTS FROM SUBCULTURED CALLUS INITIATED FROM NEEDLE ADVENTITIOUS BUDS

Plantlets were regenerated from cultures established from Pinus sylves tris (Scots pine) meristematic tissue. Seedling explants were first st imulated to develop axillary buds. Developing axillary buds produced n umerous new meristems that gave rise to globular adventitious buds loc ated along the needles on half-strength modified Murashige and Skoog m edium supplemented with coconut milk and 6-benzylaminopurine. A histol ogical study showed that these new buds originated from dedifferentiat ed mesophyll and epidermal tissues of the needles. Some of these buds were used for the regeneration of whole plantlets, others were excised and transferred to woody plant medium, on which calli developed at th e bases of the microcuttings. These calli were organogenic when subcul tured on a hormone-free medium and initiated a large number of rooted plantlets that showed high potential to multiply themselves indefinite ly. This is the first report of regeneration of Scots pine from a subc ulturable organogenic line. Mycorrhizae were initiated for both types of plantlets with Hebeloma cylindrosporum on a perlite substrate under fully controlled conditions. Mycorrhizae improved the transfer of the plantlets to ex vitro conditions.